Items such as Diamond armor and shulkers or contents inside shulkers have started randomly disappearing. At first we throught it was a thief (because we've had history of robbings in the past) but found out everyone we've deeply investigated didn't have the items. Another reason why we figured out it was a bug was because someone reported that their shulker box that was in their ender chest was completely empty of its contents. I've done research and found out this was an issue in the past but was resolved. I believe this issue came back due to the hotfix. 

Edit; upon further investigation we've found out that the people who's had this happen to them didn't save properly or hard closed the application after putting the items away.